(a) Field of the Invention
The invention relates to the use of antisense oligonucleotides directed against specific cellular receptors, alone or in combination, in order to inhibit the inflammatory reaction that is present in asthma, hypereosinophilia or atopic diseases and to inhibit neoplastic cell proliferation.
(b) Description of Prior Art
Antisense oligonucleotides are a new class of pharmaceuticals. In general, antisense refers to the use of small, synthetic oligonucleotides, with the same constituents as that found in our own DNA and which resemble single stranded DNA. The antisense oligonucleotides are designed as a mirror sequence of a part of a gene they are targeting in order to be able to adhere to this sequence and inhibit gene expression. Gene expression is inhibited through hybridization of sense oligonucleotide to a specific messenger RNA (mRNA) sense target according to the Watson-Crick base pairing in which adenosine and thymidine or guanosine and cytidine interact through hydrogen bonding. These simple base-pairing rules govern the interaction between the antisense oligonucleotides and the cellular RNA, which allow to design an antisense oligonucleotide. A major advantage of this new strategy is the specificity of action with the potential for less side effects and toxicity. This therapeutic strategy could potentially be applied to any disease where an overexpression of one or several genes is believed to cause the presence or persistence of the disease. As a result, there have been numerous studies of antisense oligonucleotides as therapeutic agents for cancer and viral diseases.
Few studies have been performed in order to assess whether antisense oligonucleotides could inhibit receptor expression on cell surfaces for inflammatory mediators.
Antisense oligonucleotides can be used to inhibit interleukin (IL)-6 receptor expression and thus the effects of the acute inflammatory mediator interleukin-6 on cells. No studies have been conducted to assess whether antisense oligonucleotides can be employed to inhibit receptors on cells that are involved in asthmatic inflammation or on cancerous cells.
Asthma is a disease that affects 5 to 10% of the population which has doubled in prevalence in the last 25 years. This increase has been noted especially in infants after a viral infection of the airways (bronchiolitis), in children and in occupational induced asthma. The exact cause of asthma is not yet known. However, it is believed that agents such as viruses are involved in the perpetuation of the abnormal inflammation that is found in the airways of patients with asthma and thus the persistence of the disease.
For this reason the current recommendations for first line therapy of asthma is a potent anti-inflammatory medication such as corticosteroids and antileukotrienes. Although this therapy is effective in many patients, some patients are resistant to corticosteroids. This medication is also a potent immunosuppressive with long term side effects and has not been shown to be effective in the prevention of allergy or asthma.
Antileukotrienes have some effect in allergy and asthma but are not as effective as corticosteroids.
Several inflammatory mediators play a role in the appearance and perpetuation of inflammation in the airways of patients with asthma. Some mediators attract the inflammatory cells into the airways either through chemotaxis of eosinophils (the chemokines: RANTES, eotaxin 1,2, MCP-3,4 that act mostly in asthmatic inflammation through a receptor called CCR3) or through endothelial cell activation (IL-4,13). Other mediators cause the priming and increased survival of inflammatory cells in the airways (IL-3,5, GM-CSF, IL-4). These mediators thus consist of either specific chemokines for eosinophils or of cytokines of the T helper lymphocyte type 2 phenotype (Th2: IL-3,4,5,13 and GM-CSF).
An improvement in asthma has been shown when there is a decrease in these inflammatory mediators in the airways.
Allergy is a disease that is extremely prevalent, for example atopic rhinitis affects around 30% of the population. Allergy is characterized by abnormal IgE production and inflammation to an allergen. In the presence of IgE and allergen, effector cells such as the mast cells degranulate and release inflammatory mediators leading to the recruitment of the same inflammatory cells that are found in asthma. In atopic rhinitis, nasal polyposis and chronic sinusitis one finds the same excess in inflammatory mediators as those present in asthma. IL-4 and IL-13 are necessary for the production of IgE and the induction of the cells with a Th2 phenotype.
Cancer is the second cause of death in humans and is characterized by abnormal proliferation of immortalized cells. One of the mechanisms that is involved in the persistence and increase in these cells is by the release of growth factors that act through receptors and lead to cellular proliferation. Amongst these growth factors, GM-CSF has been shown to be an important growth factor for several tumor cells. The inhibition of proliferation of cancerous cells by blocking the receptors for growth factors could be important in the therapy of certain cancers.
It would be desirable to be provided with the use of antisense oligonucleotides directed against at least one specific common receptor for either Th2 cytokines or receptor for mediators that attract cells that respond to Th2 cytokines, in order to inhibit the inflammatory reaction that is present in asthma or atopy and to inhibit neoplastic cell proliferation.
It would also be highly desirable to be provided with antisense oligonucleotides directed against a nucleic acid sequence coding for receptors so that by inhibiting these receptors these oligonucleotides could be employed in the therapy and/or prevention of asthma, allergy, general inflammation and cancer.